There is a significant stigma attached to mental illness in the U.S. and this stigma is believed to contribute to an estimated 41% of individuals with serious mental illness who are not in treatment. To address this problem, California recently launched a $60 million publically-financed mental illness Stigma and Discrimination Reduction (SDR) initiative. The SDR draws from theories of mental illness stigma reduction and a growing but methodologically limited body of evidence examining similar efforts in other countries. The California initiative's centerpiece is a major social marketing campaign, supplemented by targeted local outreach to general audiences, stakeholders, and key influence groups. Activities are expected to reach millions of individuals across the state. Targeted outcomes are improved mental illness knowledge, reduced public stigma, and increased early identification and treatment-seeking for those with symptoms of mental illness. The effort has already been touted as a model for the nation. We propose to test the effects of the SDR initiative on CA adults experiencing mild to severe symptoms of mental distress by 1) tracking levels of mental illness related self-stigma and experienced discrimination in this population from mid to post initiative, 2) testing whether any shifts in illness recognition, treatment seeking, and functioning in this group are greater than shifts experienced by comparable individuals residing in other states, and 3) testing for processes explaining any observed shifts in self-stigma and treatment seeking. We plan to leverage data from a longitudinal survey of a representative sample of CA adults (N=1258) and a mid-initiative benchmarking survey of a representative sample of CA adults experiencing mental distress (N=1066), both conducted as part of the legislatively mandated evaluation of the SDR. We will supplement these with a post-initiative cross-sectional survey and data from the National Survey of Drug Use and Health (NSDUH) collected pre and post initiative. Propensity matching the NSDUH samples of California adults with NSDUH participants outside the state will provide an equivalent comparison. The research is a unique opportunity to test the effectiveness of a major mental health initiative, will enhance our scientiic understanding of stigma reduction efforts and their mechanisms of action, and have important implications for the design of future initiatives employing stigma reduction as a method of improving mental health.